The present invention relates to a shelf positioning mechanism for sectional rack, and more particularly to a shelf positioning mechanism that allows the same shelves of a sectional rack to be selectively turned upside down when they are assembled onto vertical posts of the sectional rack.
A sectional rack that can be assembled and erected without the need of any tool is most welcomed by consumers. Such sectional rack usually includes many metal tubes as its posts, and these posts are provided with a plurality of spaced annular grooves, making the posts looked like bamboo poles. The sectional rack also includes a plurality of horizontal shelves being assembled onto the posts by putting short sleeves provided at corners of each shelf around connecting members previously attached to the posts at the annular grooves. U.S. Pat. Nos. 5,676,263; 5,303,645; 5,174,676; 4,991,725; 4,799,818; 4,595,107; 5,546,887; and 4,763,799 all disclose sectional racks using such bamboo pole-like tubes as the posts of the rack. Please refer to FIG. 1. The above-described conventional sectional rack includes vertical posts 10 with annular grooves 11 spaced on an outer wall thereof for engaging with ribs 21 provided on an inner wall surface of the connecting members 20, so that the connecting members 20 are attached to the posts 10 at the annular grooves 11. Each of the connecting members has varying outer diameters gradually increased from top to bottom. Each of the shelves 30 has a short sleeve 31 provided at each corner thereof (only two of four corners are shown in the drawing). The short sleeve 31 has varying inner diameters gradually increased from top to bottom corresponding to the varying outer diameters of the connecting members 20. When the shelf 30 is assembled onto the vertical posts 10, the short sleeves 31 are put around the connecting members 20 to tightly clamp the latter against the posts 10 at the annular grooves 11 and therefore hold the shelf 30 to the posts 10 at four corners.
The shelf 30 shown in FIG. 1 includes a plurality of horizontal metal wires 32 that together form a carrying surface at an open upper side of the shelf 30. The shelf 30 with the carrying surface formed at the open upper side thereof is referred to as a regular shelf, and things laid on the regular shelf 30 are completely visible. However, the sectional rack may also have shelves 30xe2x80x2 that include a plurality of horizontal metal wires 32xe2x80x2 forming a carrying surface at an enclosed lower side of the shelf 30xe2x80x2, as shown in FIG. 2. The shelf 30xe2x80x2 with the carrying surface formed at the enclosed lower side thereof is referred to as a reverse shelf, and things laid on the reverse shelf are protected from falling out of the shelf. The regular and the reverse shelves 30, 30xe2x80x2 have their respective advantages and are selected for use depending on users"" actual need and preference. However, it is troublesome but necessary for a sectional rack manufacturer to decide and produce the required numbers of the regular and the reverse shelves 30, 30xe2x80x2 for constructing a set of the above-described sectional rack according to a customer""s order.
It is a primary object of the present invention to provide a shelf positioning mechanism for sectional rack that enables the same one shelf to be used either as a regular or a reverse shelf when the shelf is assembled onto posts of the sectional rack.
To achieve the above and other objects, the shelf positioning mechanism for sectional rack according to the present invention mainly include a positioning member to be fitted between the short sleeve provided at each corner of the shelf and the connecting member configured to attach to the vertical post at the annular groove. The positioning member has downward and outward inclined inner wall surface that applies a clamping force on the downward and outward inclined outer wall surface of the connecting member, and has straight outer wall surface to tightly bear against a straight inner wall surface of the short sleeve. Therefore, the same shelf can be selectively turned upside down when it is assembled onto the vertical posts.
The positioning member is provided around a lower end with radially outward projected flanges, on which the short sleeve of the shelf is rested to ensure tight fitness of the straight inner wall surface of the short sleeve with the straight outer wall surface of the positioning member.
In a preferred embodiment, the positioning member includes two complementary parts that are closable to each other to form a hollow cylindrical member, such that when the positioning member is put around the connecting member and subjected to a resistance from the connecting member, it is slightly expanded to tightly bear against the inner wall surface of the short sleeve, causing the connecting member, the positioning member, and the short sleeve to form a sequentially and securely connected unit.